Communication Method and Related Device

ABSTRACT

A communication method and a related device, the method including receiving a radio access capability of a terminal device, detecting whether a target radio access capability the same as the received radio access capability of the terminal device exists in a terminal device access capability set, where the terminal device access capability set is a set of radio access capability information corresponding to radio access capabilities, and, when the target radio access capability exists in the terminal device access capability set, indexing second access capability indication information in a context of the terminal device to radio access capability information corresponding to the target radio access capability.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Application No.PCT/CN2018/085630, filed on May 4, 2018, which claims priority toChinese Patent Application No. 201710313985.7, filed on May 5, 2017. Thedisclosures of the aforementioned applications are hereby incorporatedby reference in their entireties.

TECHNICAL FIELD

The present invention relates to the field of communicationstechnologies, and in particular, to a communication method and a relateddevice.

BACKGROUND

In the mobile communications field, a radio access capability of aterminal device is an important factor for a base station to determineair interface configuration. Therefore, when the terminal device entersa connected mode, the base station performs air interface configurationbased on the radio access capability of the terminal device. In afourth-generation mobile communications technology, the radio accesscapability of the terminal device is stored by using a core network.After an RRC (radio resource control) connection between the terminaldevice and the base station is set up, the base station obtains theradio access capability of the terminal device from the core network. Ifthe core network stores the radio access capability of the terminaldevice, the core network directly sends the radio access capability ofthe terminal device to the base station, to enable the base station toperform air interface configuration. If the core network does not storethe radio access capability of the terminal device, the base stationobtains the radio access capability of the terminal device from theterminal device again.

A current manner for obtaining the radio access capability of theterminal device consumes a relatively long time, leading to a longaccess delay and relatively low communication performance, and can nolonger adapt to increasingly higher requirements of current users forcommunication quality.

SUMMARY

Embodiments of this application provide a communication method and arelated device. An access network device can obtain a radio accesscapability of a terminal device as quickly as possible, to reduce anaccess delay, and improve communication performance.

A first aspect of this application provides a communication method. In aradio resource control RRC connection setup procedure, an access networkdevice receives first access capability indication information of aterminal device, where the first access capability indicationinformation is used to represent a radio access capability of theterminal device, and the access network device obtains the radio accesscapability of the terminal device according to the first accesscapability indication information.

In this technical solution, in the RRC connection setup procedure, theaccess network device can obtain or start to obtain the radio accesscapability of the terminal device, so that air interface configurationcan be delivered more quickly, communication performance is improved,and an access delay is reduced.

In a first possible implementation of the first aspect, the accessnetwork device uses a radio access capability that corresponds to thefirst access capability indication information and that is in a firstterminal device access capability set as the radio access capability ofthe terminal device according to the first access capability indicationinformation.

In this technical solution, the access network device stores the radioaccess capability of the terminal device. An air interface only needs totransmit the first access capability indication information, and doesnot need to transmit the radio access capability, so that signalingoverheads of the air interface are reduced.

With reference to the first aspect or the first possible implementationof the first aspect, in a second possible implementation of the firstaspect, when the access network device does not store the radio accesscapability that corresponds to the first access capability indicationinformation, the access network device requests the terminal device or acore network device for the radio access capability of the terminaldevice.

In this technical solution, in the RRC connection setup procedure, ifdetermining that the radio access capability that corresponds to thefirst access capability indication information does not exist, theaccess network device may immediately initiate a process of requestingthe terminal device or the core network device for the radio accesscapability of the terminal device, so that air interface configurationcan be delivered more quickly, communication performance is improved,and an access delay is reduced.

With reference to the second possible implementation of the firstaspect, in a third possible implementation of the first aspect, afterrequesting the terminal device for the radio access capability of theterminal device, the access network device receives terminal deviceaccess capability information sent by the terminal device, where theterminal device access capability information includes the radio accesscapability of the terminal device, and the access network devicecorrespondingly adds the first access capability indication informationof the terminal device and the radio access capability of the terminaldevice to the first terminal device access capability set.

In this technical solution, the access network device correspondinglyadds the first access capability indication information of the terminaldevice and the radio access capability of the terminal device to thefirst terminal device access capability set, so that when the terminaldevice reenters a connected mode, the access network device can directlyfind, in the first terminal device access capability set, the radioaccess capability that is of the terminal device and that corresponds tothe first access capability indication information without requestingthe terminal device for the radio access capability, so that airinterface configuration can be delivered more quickly, communicationperformance is improved, and an access delay is reduced.

With reference to the first possible implementation of the first aspect,in a fourth possible implementation of the first aspect, after using theradio access capability that corresponds to the first access capabilityindication information and that is in the first terminal device accesscapability set as the radio access capability of the terminal device,the access network device sends a first message to the core networkdevice, where the first message is used to indicate that the accessnetwork device has obtained the radio access capability of the terminaldevice.

In this technical solution, the access network device has obtained theradio access capability of the terminal device, and the core networkdevice does not need to send the radio access capability of the terminaldevice to the access network device, so that signaling overheads arereduced.

With reference to the second possible implementation of the firstaspect, in a fifth possible implementation of the first aspect, afterrequesting the core network device for the radio access capability ofthe terminal device, the access network device receives a third messagefrom the core network device, and when the third message carries theradio access capability of the terminal device, the access networkdevice correspondingly adds the first access capability indicationinformation of the terminal device and the radio access capability ofthe terminal device to the first terminal device access capability set.

In this technical solution, the access network device correspondinglyadds the first access capability indication information of the terminaldevice and the radio access capability of the terminal device to thefirst terminal device access capability set, so that when the terminaldevice reenters a connected mode, the access network device can directlyfind, in the first terminal device access capability set, the radioaccess capability that is of the terminal device and that corresponds tothe first access capability indication information without requestingthe terminal device for the radio access capability, so that airinterface configuration can be delivered more quickly, communicationperformance is improved, and an access delay is reduced.

With reference to the first aspect or any one of the first to fifthpossible implementations of the first aspect, in a sixth possibleimplementation of the first aspect, the first access capabilityindication information of the terminal device includes terminal devicemodel information or a radio access capability identifier.

With reference to the first aspect or any one of the first to sixthpossible implementations of the first aspect, in a seventh possibleimplementation of the first aspect, when it is determined to performaccess network device handover on the terminal device, the accessnetwork device sends a fourth message carrying the first accesscapability indication information to a target access network device.

In this technical solution, the access network device sends the fourthmessage carrying the first access capability indication information tothe target access network device, only needs to transmit the firstaccess capability indication information, and does not need to transmitthe radio access capability, so that signaling overheads are reduced.

With reference to the first aspect or any one of the first to seventhpossible implementations of the first aspect, in an eighth possibleimplementation of the first aspect, the first access capabilityindication information is carried by an RRC connection request messageor an RRC connection setup complete message.

A second aspect of this application provides another communicationmethod. A terminal device obtains first access capability indicationinformation of the terminal device, and in a radio resource control RRCconnection setup procedure, the terminal device sends the first accesscapability indication information of the terminal device to an accessnetwork device, where the first access capability indication informationis used to represent a radio access capability of the terminal device.

In this technical solution, in the RRC connection setup procedure of theaccess network device, the terminal device sends the first accesscapability indication information of the terminal device to the accessnetwork device, and the access network device can obtain or start toobtain the radio access capability of the terminal device, so that airinterface configuration can be delivered more quickly, communicationperformance is improved, and an access delay is reduced.

In a first possible implementation of the second aspect, when a radioaccess capability corresponding to the first access capabilityindication information does not exist in a first terminal device accesscapability set, the terminal device receives a terminal device accesscapability request from the access network device.

With reference to the second aspect or the first possible implementationof the second aspect, in a second possible implementation of the secondaspect, the first access capability indication information of theterminal device includes terminal device model information or a radioaccess capability identifier.

A third aspect of this application provides another communicationmethod. A core network device receives a second message from an accessnetwork device, where the second message carries first access capabilityindication information of a terminal device, and the first accesscapability indication information is used to represent a radio accesscapability of the terminal device, and the core network device obtainsthe radio access capability of the terminal device according to thefirst access capability indication information of the terminal device.

In a first possible implementation of the third aspect, the core networkdevice uses a radio access capability that corresponds to the firstaccess capability indication information and that is in a secondterminal device access capability set as the radio access capability ofthe terminal device according to the first access capability indicationinformation, and the core network device sends the obtained radio accesscapability of the terminal device to the access network device.

With reference to the first possible implementation of the third aspect,in a second possible implementation of the third aspect, when the radioaccess capability that corresponds to the first access capabilityindication information does not exist in the second terminal deviceaccess capability set, the core network device instructs the accessnetwork device to request the terminal device for the radio accesscapability of the terminal device.

With reference to the second possible implementation of the thirdaspect, in a third possible implementation of the third aspect, afterinstructing the access network device to request the terminal device forthe radio access capability of the terminal device, the core networkdevice receives the radio access capability of the terminal device fromthe access network device, and the core network device correspondinglyadds the first access capability indication information of the terminaldevice and the radio access capability of the terminal device to thesecond terminal device access capability set.

In this technical solution, the core network device correspondingly addsthe first access capability indication information of the terminaldevice and the radio access capability of the terminal device to thesecond terminal device access capability set, so that when the terminaldevice reenters a connected mode, the core network device can directlyfind, in the second terminal device access capability set, the radioaccess capability that is of the terminal device and that corresponds tothe first access capability indication information, so that the accessnetwork device can obtain the radio access capability of the terminaldevice as early as possible. In this way, air interface configurationcan be delivered more quickly, communication performance is improved,and an access delay is reduced.

With reference to the third aspect or the first to third possibleimplementations of the third aspect, in a fourth possible implementationof the third aspect, the first access capability indication informationof the terminal device includes terminal device model information or aradio access capability identifier.

A fourth aspect of this application provides another communicationmethod. A network device receives a radio access capability of aterminal device, and detects whether a target radio access capabilitythe same as the received radio access capability of the terminal deviceexists in a third terminal device access capability set, where the thirdterminal device access capability set is a set of radio accesscapability information corresponding to radio access capabilities, andwhen the target radio access capability exists in the third terminaldevice access capability set, indexes second access capabilityindication information in a context of the terminal device to radioaccess capability information corresponding to the target radio accesscapability.

In a first possible implementation of the fourth aspect, when the targetradio access capability does not exist in the third terminal deviceaccess capability set, radio access capability information correspondingto the radio access capability of the terminal device is added to thethird terminal device access capability set, and the second accesscapability indication information in the context of the terminal deviceis indexed to the added radio access capability information.

With reference to the fourth aspect or the first possible implementationof the fourth aspect, in a second possible implementation of the fourthaspect, a first access capability that has a byte stream the same asthat of the radio access capability of the terminal device and that isin the third terminal device access capability set is determined as thetarget radio access capability.

In this technical solution, provided that radio access capabilities arethe same, different terminal devices only need to store one radio accesscapability, and the context does not store the radio access capabilityof the terminal device, and instead, stores only the second accesscapability indication information for being indexed to the radio accesscapability of the terminal device, so that memory occupation of theaccess network device and the core network device by storage of theradio access capability of the terminal device can be reduced.

A fifth aspect of this application provides an access network device.The access network device includes a processor, a memory, and acommunications interface. The processor is connected to the memory andthe communications interface. For example, the processor may beconnected to the memory and the communications interface by using a bus.The communications interface is configured to communicate with anothernetwork device. The memory is configured to store a radio accesscapability and the like. The processor is configured to perform some orall of the procedures of the first aspect.

A sixth aspect of this application provides another access networkdevice, including a receiving module and a processing module.Optionally, a sending module is further included. The processing moduleis configured to implement the processor in the fifth aspect, and thesending module in combination with the receiving module is configured toimplement the communications interface in the fifth aspect. The accessnetwork device implements some or all of the methods in the first aspectby using the foregoing modules.

A seventh aspect of this application provides a storage medium. Thestorage medium stores program code. When run by a computing device, theprogram code performs the communication method provided by the firstaspect or any implementation of the first aspect. The storage mediumincludes but is not limited to a flash memory, a hard disk drive (HDD),or a solid state drive (SSD).

An eighth aspect of this application provides a computer programproduct. When run by a computing device, the computer program productperforms the communication method provided by the first aspect or anyimplementation of the first aspect.

A ninth aspect of this application provides a terminal device. Theterminal device includes a processor, a memory, and a communicationsinterface. The processor is connected to the memory and thecommunications interface. For example, the processor may be connected tothe memory and the communications interface by using a bus. Thecommunications interface is configured to communicate with anothernetwork device. The memory is configured to store a radio accesscapability and the like. The processor is configured to perform some orall of the procedures of the second aspect.

A tenth aspect of this application provides another terminal device,including a sending module and a processing module. Optionally, areceiving module is further included. The processing module isconfigured to implement the processor in the ninth aspect, and thesending module in combination with the receiving module is configured toimplement the network interface in the ninth aspect. The terminal deviceimplements some or all of the methods in the second aspect by using theforegoing modules.

An eleventh aspect of this application provides a storage medium. Thestorage medium stores program code. When run by a computing device, theprogram code performs the communication method provided by the secondaspect or any implementation of the second aspect. The storage mediumincludes but is not limited to a flash memory, a hard disk drive (HDD),or a solid state drive (SSD).

A twelfth aspect of this application provides a computer programproduct. When run by a computing device, the computer program productperforms the communication method provided by the second aspect or anyimplementation of the second aspect.

A thirteenth aspect of this application provides a core network device.The core network device includes a processor, a memory, and acommunications interface. The processor is connected to the memory andthe communications interface. For example, the processor may beconnected to the memory and the communications interface by using a bus.The communications interface is configured to communicate with anothernetwork device. The memory is configured to store a radio accesscapability and the like. The processor is configured to perform some orall of the procedures of the third aspect.

A fourteenth aspect of this application provides another core networkdevice, including a receiving module and a processing module.Optionally, a sending module is further included. The processing moduleis configured to implement the processor in the thirteenth aspect, andthe sending module in combination with the receiving module isconfigured to implement the communications interface in the thirteenthaspect. The core network device implements some or all of the methods inthe third aspect by using the foregoing modules.

A fifteenth aspect of this application provides a storage medium. Thestorage medium stores program code. When run by a computing device, theprogram code performs the communication method provided by the thirdaspect or any implementation of the third aspect. The storage mediumincludes but is not limited to a flash memory, a hard disk drive (HDD),or a solid state drive (SSD).

A sixteenth aspect of this application provides a computer programproduct. When run by a computing device, the computer program productperforms the communication method provided by the third aspect or anyimplementation of the third aspect.

A seventeenth aspect of this application provides a network device. Thenetwork device includes a processor, a memory, and a communicationsinterface. The processor is connected to the memory and thecommunications interface. For example, the processor may be connected tothe memory and the communications interface by using a bus. Thecommunications interface is configured to communicate with anothernetwork device. The memory is configured to store a radio accesscapability and the like. The processor is configured to perform some orall of the procedures of the fourth aspect.

An eighteenth aspect of this application provides another networkdevice, including a receiving module and a processing module. Theprocessing module is configured to implement the processor in theseventeenth aspect, and the receiving module is configured to implementthe communications interface in the seventeenth aspect. The networkdevice implements some or all of the methods in the fourth aspect byusing the foregoing modules.

A nineteenth aspect of this application provides a storage medium. Thestorage medium stores program code. When run by a computing device, theprogram code performs the communication method provided by the fourthaspect or any implementation of the fourth aspect. The storage mediumincludes but is not limited to a flash memory, a hard disk drive (HDD),or a solid state drive (SSD).

A twentieth aspect of this application provides a computer programproduct. When run by a computing device, the computer program productperforms the communication method provided by the fourth aspect or anyimplementation of the fourth aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

To describe the technical solutions in the embodiments of the presentinvention or in the prior art more clearly, the following brieflydescribes the accompanying drawings required for describing theembodiments or the prior art. Apparently, the accompanying drawings inthe following description show merely some embodiments of the presentinvention, and a person of ordinary skill in the art may derive otherdrawings from these accompanying drawings without creative efforts.

FIG. 1 is a schematic architectural diagram of a communications systemaccording to an embodiment of this application;

FIG. 2a is a schematic flowchart of a communication method according toan embodiment of this application;

FIG. 2b is a schematic flowchart of another communication methodaccording to an embodiment of this application;

FIG. 3a is a schematic flowchart of another communication methodaccording to an embodiment of this application;

FIG. 3b is a schematic flowchart of another communication methodaccording to an embodiment of this application;

FIG. 4a is a schematic flowchart of another communication methodaccording to an embodiment of this application;

FIG. 4b -1 and FIG. 4b -2 are a schematic flowchart of anothercommunication method according to an embodiment of this application;

FIG. 4c -1 and FIG. 4c -2 are a schematic flowchart of anothercommunication method according to an embodiment of this application;

FIG. 5a -1 and FIG. 5a -2 are a schematic flowchart of anothercommunication method according to an embodiment of this application;

FIG. 5b -i and FIG. 5b -2 are a schematic flowchart of anothercommunication method according to an embodiment of this application;

FIG. 6 is a schematic flowchart of another communication methodaccording to an embodiment of this application;

FIG. 7 is a schematic flowchart of another communication methodaccording to an embodiment of this application;

FIG. 8a is a schematic diagram of a radio access capability indexingmanner according to an embodiment of this application;

FIG. 8b is a schematic diagram of another radio access capabilityindexing manner according to an embodiment of this application;

FIG. 9 is a schematic structural diagram of an access network deviceaccording to an embodiment of this application;

FIG. 10 is a schematic structural diagram of a terminal device accordingto an embodiment of this application;

FIG. 11 is a schematic structural diagram of a core network deviceaccording to an embodiment of this application;

FIG. 12 is a schematic structural diagram of a network device accordingto an embodiment of this application;

FIG. 13 is a schematic structural diagram of another access networkdevice according to an embodiment of this application;

FIG. 14 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application;

FIG. 15 is a schematic structural diagram of another core network deviceaccording to an embodiment of this application; and

FIG. 16 is a schematic structural diagram of another network deviceaccording to an embodiment of this application.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The following clearly describes the technical solutions in theembodiments of this application with reference to the accompanyingdrawings in the embodiments of this application.

FIG. 1 is a schematic architectural diagram of a communications systemaccording to an embodiment of this application. Network elements andinterfaces are described as follows.

A core network device may be a mobility management entity (MME)/servinggateway (S-GW), or a core network device in a future 5^(th) generation(5G) system. The MME is a key control node in 3^(rd) generationpartnership project (3GPP) long term evolution (LTE), is a networkelement of a core network, and is mainly responsible for a signalprocessing part, that is, a control plane function, including functionssuch as an access control function, a mobility management function,attach and detach functions, a session management function, and agateway selection function. The S-GW is an important network element ofthe core network in the 3GPP LTE, and is mainly responsible for a userplane function for forwarding user data, that is, routing and forwardinga data packet under control of the MME.

An access network device may be a base station. The base station may bean evolved NodeB (eNodeB, eNB) in a long term evolution (LTE) network,or a base station in the future 5G system, or the like. The accessnetwork device is mainly responsible for functions on an air interfaceside, such as a radio resource management function, a quality of service(QoS) management function, and data compression and encryptionfunctions. Toward the core network side, the base station is mainlyresponsible for forwarding control plane signaling to the MME andforwarding user plane service data to the S-GW.

A terminal device may be user equipment (UE). The UE is a device thataccesses a network side by using the base station in LTE, and forexample, may be a handheld terminal device, a notebook computer, oranother device that can access a network. The UE communicates with thebase station by using an air interface technology. The air interfacetechnology may include a 4^(th) generation (4G) (for example, FDD LTE orTDD LTE) system, a future forthcoming 5G system, and the like.

The communication method of this embodiment of the present invention ismainly applied to communication between the UE and the access networkdevice and communication between the access network device and the corenetwork device. For the 4G system, the access network device is the basestation in the foregoing descriptions, and the core network device isthe MME in the foregoing descriptions. For the 5G system, there may bedifferent names, and this is not limited herein. It may be understoodthat FIG. 1 is merely an example, and this embodiment of thisapplication is not limited thereto.

Referring to FIG. 2a and FIG. 2 b, an embodiment of this applicationprovides a schematic flowchart of a communication method. In thisembodiment, an access network device maintains and stores a radio accesscapability of a terminal device, and a core network device does notmaintain and store the radio access capability of the terminal device.The method includes but is not limited to the following steps.

S102: In a radio resource control RRC connection setup procedure, theterminal device sends first access capability indication information ofthe terminal device to the access network device.

When entering a connected mode, the terminal device performs the RRC(Radio Resource Control, radio resource control) connection setupprocedure with the access network device. For example, the terminaldevice first sends an RRC connection request message (RRC CONNECTIONREQUEST) to the access network device, to request to establish an RRCconnection. The access network device sends an RRC connection setupmessage (RRC CONNECTION SETUP) to the terminal device. After determiningthat the RRC connection is successfully set up, the terminal devicesends an RRC connection setup complete message (RRC CONNECTION SETUPCOMPLETE) to the access network device, so that the RRC connection setupprocedure ends.

In the RRC connection setup procedure, the terminal device may send thefirst access capability indication information of the terminal device tothe access network device. The first access capability indicationinformation may be used to represent the radio access capability of theterminal device. To be specific, the access network device maydetermine, according to the first access capability indicationinformation, the radio access capability of the terminal device that isindicated by the first access capability indication information.

Optionally, the first access capability indication information may becarried by the RRC connection request message or the RRC connectionsetup complete message. In other words, when sending the RRC connectionrequest message or the RRC connection setup complete message to theaccess network device, the terminal device may carry the first accesscapability indication information in the RRC connection request messageor the RRC connection setup complete message. Specifically, the firstaccess capability indication information may be carried by a reservedbit in the RRC connection request message or the RRC connection setupcomplete message, or a bit may be added to the RRC connection requestmessage or the RRC connection setup complete message to carry the firstaccess capability indication information. This is not specificallylimited herein.

The radio access capability of the terminal device is a capabilityrelated to a radio air interface of the terminal device, for example, arate of the radio air interface, or a packet loss rate of the radio airinterface.

During specific implementation, the first access capability indicationinformation of the terminal device may be terminal device modelinformation or a radio access capability identifier. The terminal devicemodel information may include a product model of the terminal deviceand/or a software version number of the terminal device. The productmodel of the terminal device is a code marked on produced terminaldevices of a same type and of different specifications by a manufacturerby using numerals or letters separately, to facilitate distinction. Thesoftware version number of the terminal device is a baseband versionnumber in a communications chip of the terminal device. The radio accesscapability identifier is an identification code corresponding to theradio access capability, and may be an identifier formed by combiningnumerals, letters, symbols, or the like, for example, 123 or C1. This isnot specifically limited in this embodiment.

After receiving the first access capability indication information ofthe terminal device, the access network device may obtain the radioaccess capability of the terminal device according to the first accesscapability indication information. In the embodiment shown in FIG. 2aand FIG. 2 b, S103 may be specifically performed.

S103: The access network device searches, in a first terminal deviceaccess capability set, for a radio access capability corresponding tothe first access capability indication information, and if the radioaccess capability corresponding to the first access capabilityindication information exists, performs S1o4, as shown in FIG. 2 a, andif the radio access capability corresponding to the first accesscapability indication information does not exist, performs S105 to S107,as shown in FIG. 2 b.

After receiving the first access capability indication information, theaccess network device may obtain the radio access capability of theterminal device with reference to the first terminal device accesscapability set.

The first terminal device access capability set is a set of accesscapability indication information and radio access capabilitiescorresponding to the access capability indication information. In otherwords, the first terminal device access capability set may include aplurality of radio access capabilities, and each radio access capabilityhas corresponding access capability indication information.

It should be noted that when the access capability indicationinformation is the terminal device model information, a plurality ofdifferent pieces of terminal device model information in the firstterminal device access capability set may correspond to a same radioaccess capability, and when the access capability indication informationis the radio access capability identifier, radio access capabilityidentifiers in the first terminal device access capability set are inone-to-one correspondence to the radio access capabilities.

Optionally, the radio access capabilities stored in the first terminaldevice access capability set may be ASN.1 encoded byte streams, or beASN.1 decoded radio access capabilities, or include both the ASN.1encoded byte streams and the ASN.1 decoded radio access capabilities.

After receiving the first access capability indication information, theterminal device searches, in the first terminal device access capabilityset, for the radio access capability corresponding to the first accesscapability indication information. It is worth mentioning that a case inwhich the first terminal device access capability set is an empty set,in other words, the first terminal device access capability set does notstore any radio access capability, is not excluded. Herein, the firstterminal device access capability set may be set information maintainedby the access network device.

For example, Table 1 and Table 2 may be tables of mapping relationshipsbetween the access capability indication information and the radioaccess capabilities in the first terminal device access capability set.The access capability indication information of Table 1 is the terminaldevice model information, and the access capability indicationinformation of Table 2 is the radio access capability identifier.

TABLE 1 Table of mapping relationships between the access capabilityindication information (the terminal device model information) and theradio access capabilities Access capability indication information(terminal device model information) Radio access capability Productmodel 1 + software version Radio access capability A number 1 Productmodel 2 + software version Radio access capability B number 2 Productmodel 3 + software version Radio access capability C number 3 . . . . ..

TABLE 2 Table of mapping relationships between the access capabilityindication information (the radio access capability identifiers) and theradio access capabilities Access capability indication information(radio access capability identifier) Radio access capability C1 Radioaccess capability A C2 Radio access capability B C3 Radio accesscapability C . . . . . .

S104: The access network device uses the radio access capability thatcorresponds to the first access capability indication information andthat is in the first terminal device access capability set as the radioaccess capability of the terminal device according to the first accesscapability indication information.

In this way, in the RRC connection setup procedure, the access networkdevice can locally obtain the radio access capability of the terminaldevice, so that air interface configuration can be delivered morequickly, communication performance is improved, and an access delay isreduced. Further, when the access network device stores the radio accesscapability of the terminal device, an air interface only needs totransmit the first access capability indication information, and doesnot need to transmit the radio access capability, so that signalingoverheads of the air interface are reduced.

As shown in FIG. 2 a, after S104, S108 may be further performed.

S105: The access network device requests the terminal device for theradio access capability of the terminal device.

If the access network device does not find, in the first terminal deviceaccess capability set, the radio access capability that corresponds tothe first access capability indication information, the access networkdevice may request the terminal device for the radio access capabilityof the terminal device. For example, the access network device requeststhe terminal device by using a UE Capability Enquiry message, forrequesting the terminal device to send the radio access capability ofthe terminal device to the access network device.

S106: The terminal device sends terminal device access capabilityinformation to the access network device.

The terminal device sends the terminal device access capabilityinformation (for example, UE Capability Information) to the accessnetwork device based on a received request for the radio accesscapability, and the terminal device access capability informationincludes the radio access capability of the terminal device. Optionally,the terminal device access capability information may further carry thefirst access capability indication information, so that the accessnetwork device correspondingly adds the first access capabilityindication information of the terminal device and the radio accesscapability of the terminal device to the first terminal device accesscapability set directly based on the terminal device access capabilityinformation.

Therefore, in the RRC connection setup procedure, if determining thatthe radio access capability that corresponds to the first accesscapability indication information does not exist, the access networkdevice may immediately initiate a process of requesting the terminaldevice for the radio access capability of the terminal device, so thatair interface configuration can be delivered more quickly, communicationperformance is improved, and an access delay is reduced.

S107: The access network device correspondingly adds the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the first terminal deviceaccess capability set.

After obtaining the radio access capability sent by the terminal device,the access network device may correspondingly add the first accesscapability indication information and the radio access capability of theterminal device to the first terminal device access capability set, inother words, complete an update of the first terminal device accesscapability set. In this way, when the terminal device reenters aconnected mode, the access network device may directly find, in thefirst terminal device access capability set, the radio access capabilitythat is of the terminal device and that corresponds to the first accesscapability indication information without requesting the terminal devicefor the radio access capability, so that air interface configuration canbe delivered more quickly, communication performance is improved, and anaccess delay is reduced.

Optionally, the radio access capability sent by the terminal device maybe an ASN.1 encoded byte stream, and the access network device maydecode the byte stream. Therefore, the radio access capabilities storedin the first terminal device access capability set may be ASN.1 encodedbyte streams or ASN.1 decoded radio access capabilities, so that theaccess network device can directly use the ASN.1 decoded radio accesscapabilities. Alternatively, both the ASN.1 encoded byte streams and thedecoded radio access capabilities may be stored. This is not limited inthis embodiment of this application.

It should be noted that there is no necessary sequence in which S106 andS107 are performed, and therefore this is not limited herein.

As shown in FIG. 2 b, after S106 or S107, S108 may be performed.

S108: The access network device performs air interface configuration onthe terminal device based on the radio access capability of the terminaldevice.

After obtaining the radio access capability of the terminal device, theaccess network device may perform air interface configuration, forexample, configure a measurement configuration parameter or a handoverparameter, based on the radio access capability of the terminal device.

Optionally, before S102, the access network device may perform S101.

S101: The access network device obtains the first terminal device accesscapability set.

After the access network device is powered on, the access network devicemay obtain an initial first terminal device access capability set byusing an OSS (Operation Support System, operation support system).

Optionally, when the access network device needs to hand over theterminal device to a target access network device, this embodiment mayfurther include the following.

S109: When it is determined to perform access network device handover onthe terminal device, the access network device sends a fourth messagecarrying the first access capability indication information to thetarget access network device.

The access network device determines the target access network device towhich the terminal device needs to be handed over, and sends the fourthmessage to the target access network device. The fourth message carriesthe first access capability indication information of the terminaldevice. After receiving the fourth message, the target access networkdevice obtains the radio access capability that is of the terminaldevice and that corresponds to the first access capability indicationinformation. Further, the fourth message may be a handover requestmessage.

The embodiment shown in FIG. 2a and FIG. 2b is applicable to animplementation scenario in which the access network device maintains andstores the radio access capability of the terminal device, the corenetwork device does not maintain and store the radio access capabilityof the terminal device, and the access network device does not deletethe stored radio access capability of the terminal device as theterminal device enters an idle mode. To be specific, the access networkdevice maintains and stores the first terminal device access capabilityset. The set is not for a particular terminal device, and is shared byUEs in the access network device. The embodiment shown in FIG. 2a andFIG. 2b is also applicable to another scenario in which the steps ofthis solution can be performed. This is not specifically limited herein.

Referring to FIG. 3a and FIG. 3 b, an embodiment of this applicationprovides a schematic flowchart of another communication method. In thisembodiment, a core network device maintains and stores a radio accesscapability of a terminal device, and an access network device does notmaintain and store the radio access capability of the terminal device(in an idle mode). The method includes but is not limited to thefollowing steps.

S201: In a radio resource control RRC connection setup procedure, theterminal device sends first access capability indication information ofthe terminal device to the access network device.

Refer to S102 for a specific implementation of S201, and details are notdescribed herein again.

S202: The access network device sends a second message to the corenetwork device.

Because the access network device does not maintain and store the radioaccess capability of the terminal device in an idle mode, afterreceiving the first access capability indication information, the accessnetwork device sends the second message to the core network device, andthe second message is used to request the core network device for theradio access capability of the terminal device.

In a possible implementation scenario, the second message may carry thefirst access capability indication information of the terminal device,for instructing the core network device to search for the correspondingradio access capability according to the first access capabilityindication information of the terminal device, and then send the radioaccess capability to the access network device. In another possibleimplementation scenario, the second message may not carry the firstaccess capability indication information of the terminal device, and isonly used for instructing the core network device to obtain the radioaccess capability of the terminal device.

Subsequent steps of this embodiment are further described by using animplementation scenario in which the second message carries the firstaccess capability indication information of the terminal device as anexample.

After receiving the second message of the access network device, thecore network device may obtain the radio access capability of theterminal device according to the first access capability indicationinformation. In the embodiment shown in FIG. 3a and FIG. 3 b, S203 maybe specifically performed.

S203: The core network device searches, in a second terminal deviceaccess capability set, for a radio access capability corresponding tothe first access capability indication information, and if the radioaccess capability corresponding to the first access capabilityindication information exists, performs S204 and S205, as shown in FIG.3 a, and if the radio access capability corresponding to the firstaccess capability indication information does not exist, performs S206to S208, as shown in FIG. 3 b.

After receiving the second message, the core network device may obtainthe radio access capability of the terminal device with reference to thesecond terminal device access capability set.

The second terminal device access capability set is a set of accesscapability indication information and radio access capabilitiescorresponding to the access capability indication information. In otherwords, the second terminal device access capability set may include aplurality of radio access capabilities, and each radio access capabilityhas corresponding access capability indication information. Herein, thesecond terminal device access capability set may be set informationmaintained by the core network device. It may be understood that amanner of maintaining the second terminal device access capability setis similar to that of maintaining the first terminal device accesscapability set, and details are not described herein again.

It should be noted that the second terminal device access capability setmay be the same as or different from the first terminal device accesscapability set.

Optionally, because the second terminal device access capability setincludes radio access capabilities of some or even all of terminaldevices managed by the core network device, a quantity of radio accesscapabilities stored in the second terminal device access capability setmay be far greater than a quantity of radio access capabilities storedin the first terminal device access capability set.

After receiving the second message, the core network device searches, inthe second terminal device access capability set, for the radio accesscapability corresponding to the first access capability indicationinformation. It is worth mentioning that a case in which the secondterminal device access capability set is an empty set, in other words,the second terminal device access capability set does not store anyradio access capability, is not excluded. Specifically, mappingrelationships between the access capability indication information andthe radio access capabilities in the second terminal device accesscapability set are consistent with those reflected in Table 1 and Table2 mentioned in S103, and details are not described herein again.

S204: The core network device uses the radio access capability thatcorresponds to the first access capability indication information andthat is in the second terminal device access capability set as the radioaccess capability of the terminal device according to the first accesscapability indication information.

S205: The core network device sends a third message to the accessnetwork device, where the third message carries the radio accesscapability of the terminal device.

The core network device sends the obtained radio access capability ofthe terminal device to the access network device by using the thirdmessage. The third message, for example, may be carried by a terminaldevice context setup request (UE CONTEXT SETUP REQUEST). To be specific,the core network device sends the terminal device context setup requestto the access network device, where the terminal device context setuprequest carries the radio access capability of the terminal device.

In the foregoing manner, in the RRC connection setup procedure, theaccess network device may initiate a process of obtaining the radioaccess capability of the terminal device to the core network device, sothat air interface configuration can be delivered more quickly,communication performance is improved, and an access delay is reduced.

As shown in FIG. 3 a, after S205, S211 may be further performed.

S206: The core network device sends the third message to the accessnetwork device, where the third message does not carry the radio accesscapability of the terminal device.

The third message does not carry the radio access capability of theterminal device, for indicating to the access network device that thecore network device does not store the radio access capability of theterminal device, and the access network device needs to request theterminal device for the radio access capability of the terminal device.The third message may be specifically carried by a context setup request(UE CONTEXT SETUP REQUEST). To be specific, the terminal device contextsetup request (UE CONTEXT SETUP REQUEST) sent by the core network devicedoes not carry the radio access capability of the terminal device, andmay indicate to the access network device that the core network devicedoes not obtain the radio access capability of the terminal device.

S207: The access network device requests the terminal device for theradio access capability of the terminal device.

Because the third message sent by the core network device does not carrythe radio access capability of the terminal device, the access networkdevice further requests the terminal device for the radio accesscapability of the terminal device, for example, requests the terminaldevice by using a UE Capability Enquiry message, for requesting theterminal device to send the radio access capability of the terminaldevice to the access network device.

S208: The terminal device sends terminal device access capabilityinformation to the access network device.

The terminal device sends the terminal device access capabilityinformation (for example, UE Capability Information) to the accessnetwork device based on a received request for the radio accesscapability, and the terminal device access capability informationincludes the radio access capability of the terminal device. Optionally,the terminal device access capability information may further carry thefirst access capability indication information, so that the accessnetwork device correspondingly adds the first access capabilityindication information of the terminal device and the radio accesscapability of the terminal device to the first terminal device accesscapability set directly based on the terminal device access capabilityinformation.

As shown in FIG. 3 b, after S208, S209 and S210 may be furtherperformed, or S211 may be further performed.

A sequence in which S209 and S211 are performed is not limited. Thesequence in which S209 and S211 are performed may be adjusted based onrequirements, or S209 and S211 may be performed simultaneously.

S209: The access network device sends the radio access capability of theterminal device to the core network device.

The radio access capability of the terminal device may be carried by aterminal device access capability information indication (UE CAPABILITYINFO INDICATION).

S210: The core network device correspondingly adds the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the second terminal deviceaccess capability set.

After obtaining the radio access capability sent by the terminal device,the core network device may correspondingly add the first accesscapability indication information and the radio access capability of theterminal device to the second terminal device access capability set, inother words, complete an update of the second terminal device accesscapability set, so that when the terminal device reenters a connectedmode, the core network device can directly find, in the second terminaldevice access capability set, the radio access capability that is of theterminal device and that corresponds to the first access capabilityindication information.

In this way, in the RRC connection setup procedure, the access networkdevice may initiate a process of obtaining the radio access capabilityof the terminal device to the core network device. When the radio accesscapability of the terminal device does not exist in the core networkdevice, the access network device can request the terminal device forthe radio access capability of the terminal device more quickly, so thatthe access network device can obtain the radio access capability of theterminal device as early as possible. In this way, air interfaceconfiguration can be delivered more quickly, communication performanceis improved, and an access delay is reduced.

S211: The access network device performs air interface configuration onthe terminal device based on the radio access capability of the terminaldevice.

Refer to S108 for a specific implementation of S211, and details are notdescribed herein again.

Optionally, when the access network device needs to hand over theterminal device to a target access network device, this embodiment mayfurther include the following.

S212: When it is determined to perform access network device handover onthe terminal device, the access network device sends a fourth messagecarrying the first access capability indication information to thetarget access network device.

Refer to S109 for a specific implementation of S212, and details are notdescribed herein again.

The embodiment shown in FIG. 3a and FIG. 3b is applicable to animplementation scenario in which the core network device maintains andstores the radio access capability of the terminal device, and theaccess network device does not maintain and store the radio accesscapability of the terminal device (in the idle mode). The embodimentshown in FIG. 3a and FIG. 3b is also applicable to another scenario inwhich the steps of this solution can be performed. This is notspecifically limited herein.

Referring to FIG. 4a to FIG. 4c -2, an embodiment of this applicationprovides a schematic flowchart of another communication method. In thisembodiment, the core network device and the access network deviceseparately maintain and store the radio access capability of theterminal. The method includes but is not limited to the following steps.

S302: In a radio resource control RRC connection setup procedure, theterminal device sends first access capability indication information ofthe terminal device to the access network device.

Refer to S102 for a specific implementation of S302, and details are notdescribed herein again.

After receiving the first access capability indication information ofthe terminal device, the access network device may obtain the radioaccess capability of the terminal device according to the first accesscapability indication information. In the embodiment shown in FIG. 4a toFIG. 4c -2, S303 may be specifically performed.

S303: The access network device searches, in a first terminal deviceaccess capability set, for a radio access capability corresponding tothe first access capability indication information, and if the radioaccess capability corresponding to the first access capabilityindication information exists, performs S304, as shown in FIG. 4 a, andif the radio access capability corresponding to the first accesscapability indication information does not exist, performs S307 to S310,as shown in FIG. 4b -1 and FIG. 4b -2, or performs S307 and S308 andS311 to S315, as shown in FIG. 4c -i and FIG. 4c -2.

Refer to S103 for a specific implementation of S303, and details are notdescribed herein again.

S304: The access network device uses the radio access capability thatcorresponds to the first access capability indication information andthat is in the first terminal device access capability set as the radioaccess capability of the terminal device according to the first accesscapability indication information.

In this way, in the RRC connection setup procedure, the access networkdevice can locally obtain the radio access capability of the terminaldevice, so that air interface configuration can be delivered morequickly, communication performance is improved, and an access delay isreduced. Further, when the access network device stores the radio accesscapability of the terminal device, an air interface only needs totransmit the first access capability indication information, and doesnot need to transmit the radio access capability, so that signalingoverheads of the air interface are reduced.

As shown in FIG. 4 a, after S304, S317 may be further performed, or S305 and S306 may be further performed.

A sequence in which S305 and S317 are performed is not limited. Thesequence in which S305 and S317 are performed may be adjusted based onrequirements, or S305 and S317 may be performed simultaneously.

S305: The access network device sends a first message to the corenetwork device.

The first message is used to indicate that the access network device hasobtained the radio access capability of the terminal device. The accessnetwork device and the core network device separately maintain and storethe radio access capability of the terminal device. Therefore, afterfinding the radio access capability of the terminal device, the accessnetwork device may notify, by using the first message, the core networkdevice that the access network device has obtained the radio accesscapability of the terminal device, and the core network device does notneed to send the radio access capability of the terminal device to theaccess network device.

S306: The core network device sends a terminal device context setuprequest to the access network device, where the terminal device contextsetup request does not carry the radio access capability of the terminaldevice.

Based on the first message, the core network device does not add theradio access capability of the terminal device in the sent terminaldevice context setup request (UE CONTEXT SETUP REQUEST), so thatsignaling overheads can be reduced.

S307: The access network device sends a second message to the corenetwork device.

Because the access network device does not find the radio accesscapability of the terminal device, the access network device sends thesecond message to the core network device, where the second message isused to request the core network device for the radio access capabilityof the terminal device.

In a possible implementation scenario, the second message may carry thefirst access capability indication information of the terminal device,for instructing the core network device to search for the correspondingradio access capability according to the first access capabilityindication information of the terminal device, and then send the radioaccess capability to the access network device. In another possibleimplementation scenario, the second message may not carry the firstaccess capability indication information of the terminal device, and isonly used for instructing the core network device to obtain the radioaccess capability of the terminal device.

Subsequent steps of this embodiment are further described by using animplementation scenario in which the second message carries the firstaccess capability indication information of the terminal device as anexample.

After receiving the second message of the access network device, thecore network device may obtain the radio access capability of theterminal device according to the first access capability indicationinformation. In the embodiment shown in FIG. 4, S308 may be specificallyperformed.

S308: The core network device searches, in a second terminal deviceaccess capability set, for a radio access capability corresponding tothe first access capability indication information, and if the radioaccess capability corresponding to the first access capabilityindication information exists, performs S309 and S310, as shown in FIG.4b -1 and FIG. 4b -2, and if the radio access capability correspondingto the first access capability indication information does not exist,performs S311 to S315, as shown in FIG. 4c -1 and FIG. 4c -2.

Refer to S203 for a specific implementation of S308, and details are notdescribed herein again.

S309: The core network device uses the radio access capability thatcorresponds to the first access capability indication information andthat is in the second terminal device access capability set as the radioaccess capability of the terminal device according to the first accesscapability indication information.

S310: The core network device sends a third message to the accessnetwork device, where the third message carries the radio accesscapability of the terminal device.

Refer to S205 for a specific implementation of S310, and details are notdescribed herein again.

As shown in FIG. 4b -1 and FIG. 4b -2, after S310, S316 may be furtherperformed, or S317 may be further performed.

In this way, in the RRC connection setup procedure, when determiningthat the radio access capability of the terminal device is not stored,the access network device may initiate a process of obtaining the radioaccess capability of the terminal device to the core network device, sothat air interface configuration can be delivered more quickly,communication performance is improved, and an access delay is reduced.

S311: The core network device sends the third message to the accessnetwork device, where the third message does not carry the radio accesscapability of the terminal device.

S312: The access network device requests the terminal device for theradio access capability of the terminal device.

S313: The terminal device sends terminal device access capabilityinformation to the access network device.

As shown in FIG. 4c -i and FIG. 4c -2, after S313, S314 and S315 may befurther performed, or S316 may be further performed, or S317 may befurther performed.

A sequence in which S314, S316, and S317 are performed is not limited.The sequence in which S314, S316, and S317 are performed may be adjustedbased on requirements, or S314, S316, and S317 may be performedsimultaneously.

S314: The access network device sends the radio access capability of theterminal device to the core network device.

S315: The core network device correspondingly adds the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the second terminal deviceaccess capability set.

Refer to descriptions of S206 to S210 for a specific implementation ofS311 to S315, and details are not described herein again.

In this way, in the RRC connection setup procedure, when determiningthat the radio access capability of the terminal device is not stored,the access network device may initiate a process of obtaining the radioaccess capability of the terminal device to the core network device.When the radio access capability of the terminal device does not existin the core network device, the access network device can request theterminal device for the radio access capability of the terminal devicemore quickly, so that the access network device can obtain the radioaccess capability of the terminal device as early as possible. In thisway, air interface configuration can be delivered more quickly,communication performance is improved, and an access delay is reduced.

S316: The access network device correspondingly adds the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the first terminal deviceaccess capability set.

Refer to S107 for a specific implementation of S316, and details are notdescribed herein again.

S317: The access network device performs air interface configuration onthe terminal device based on the radio access capability of the terminaldevice.

Refer to S108 for a specific implementation of S317, and details are notdescribed herein again.

Optionally, before S302, the access network device may perform S301.

S301: The access network device obtains the first terminal device accesscapability set.

After the access network device is powered on, the access network devicemay obtain the initial first terminal device access capability set byusing an OSS (Operation Support System, operation support system).Alternatively, when an interface between the core network device and theaccess network device is set up, the core network device sends thesecond terminal device access capability set maintained by the corenetwork device to the access network device as the first terminal deviceaccess capability set of the access network device. Further, whensubsequently newly adding the radio access capability and thecorresponding access capability indication information, the core networkdevice may also send the radio access capability and the correspondingaccess capability indication information to the access network device,so that the access network device can also update the first terminaldevice access capability set.

Optionally, when the access network device needs to hand over theterminal device to a target access network device, this embodiment mayfurther include the following.

S318: When it is determined to perform access network device handover onthe terminal device, the access network device sends a fourth messagecarrying the first access capability indication information to thetarget access network device.

Refer to S109 for a specific implementation of S318, and details are notdescribed herein again.

The embodiment shown in FIG. 4a to FIG. 4c -2 is applicable to animplementation scenario in which the core network device and the accessnetwork device separately maintain and store the radio access capabilityof the terminal device, and is also applicable to another scenario inwhich the steps of this solution can be performed. This is notspecifically limited herein.

Referring to FIG. 5a -1 to FIG. 5b -2, an embodiment of this applicationprovides a schematic flowchart of another communication method. In thisembodiment, the core network device and the access network devicetogether maintain and store the radio access capability of the terminal.The method includes but is not limited to the following steps.

S402: In a radio resource control RRC connection setup procedure, theaccess network device detects whether first access capability indicationinformation of the terminal device is received.

In the radio resource control RRC connection setup procedure, theterminal device may send an RRC connection request message or an RRCconnection setup complete message to the access network device. Theaccess network device may detect whether the RRC connection requestmessage or the RRC connection setup complete message sent by theterminal device carries the first access capability indicationinformation of the terminal device. In this embodiment, the first accesscapability indication information of the terminal device may be a radioaccess capability identifier. The radio access capability identifier isan identification code corresponding to the radio access capability, andmay be an identifier formed by combining numerals, letters, symbols, orthe like, for example, 123 or C1. This is not specifically limited inthis embodiment. The radio access capability identifier may be allocatedby the core network device to the terminal device when the terminaldevice initially accesses a network (that is, allocated in subsequentS411).

S403: If the access network device does not receive the first accesscapability indication information of the terminal device, the accessnetwork device requests the terminal device for the radio accesscapability of the terminal device.

In this embodiment, when the access network device does not receive thefirst access capability indication information of the terminal device,it may be considered that the core network device does not know thefirst access capability indication information corresponding to theradio access capability of the terminal device, or the core networkdevice even does not know the radio access capability of the terminaldevice, so that the core network device does not allocate the firstaccess capability indication information to the terminal device.

Therefore, the access network device may directly request the terminaldevice for the radio access capability of the terminal device. Forexample, the access network device requests the terminal device by usinga UE Capability Enquiry message, for requesting the terminal device tosend the radio access capability of the terminal device to the accessnetwork device, so that the access network device can obtain the radioaccess capability of the terminal device by using the terminal deviceearlier, and does not need to request the core network device and thenrequest the terminal device for the radio access capability of theterminal device.

S404: The terminal device sends terminal device access capabilityinformation to the access network device.

Refer to S208 for a specific implementation of S404, and details are notdescribed herein again.

Further, after S404, S405 and S406 may be further performed.

S405: The access network device sends the radio access capability of theterminal device to the core network device.

Refer to S209 for a specific implementation of S405, and details are notdescribed herein again.

S406: The core network device searches, in the second terminal deviceaccess capability set, for a target radio access capability consistentwith the radio access capability of the terminal device, if the targetradio access capability exists, performs S407, as shown in FIG. 5a -1and FIG. 5a -2, if the target radio access capability does not exist,performs S408, as shown in FIG. 5b -1 and FIG. 5b -2.

The second terminal device access capability set is a set of accesscapability indication information and radio access capabilitiescorresponding to the access capability indication information. In otherwords, the second terminal device access capability set may include aplurality of radio access capabilities, and each radio access capabilityhas corresponding access capability indication information. In thisembodiment, the access capability indication information is the radioaccess capability identifier, and radio access capability identifiers inthe second terminal device access capability set are in one-to-onecorrespondence to the radio access capabilities. Specifically, mappingrelationships between the access capability indication information andthe radio access capabilities in the second terminal device accesscapability set are consistent with those reflected in Table 2 mentionedin S103, and details are not described herein again.

Optionally, a byte stream of the radio access capability of the terminaldevice may be compared with a byte stream of each radio accesscapability in the second terminal device access capability set. If thereis a target radio access capability with a completely consistent bytestream, it is determined that the target radio access capability isconsistent with the radio access capability of the terminal device, thatis, the target radio access capability is the radio access capability ofthe terminal device. If there is no radio access capability with acompletely consistent byte stream, it is determined that a target radioaccess capability consistent with the radio access capability of theterminal device does not exist in the second terminal device accesscapability set. It is worth mentioning that a case in which the secondterminal device access capability set is an empty set, in other words,the second terminal device access capability set does not store anyradio access capability, is not excluded herein. In this case, a targetradio access capability consistent with the radio access capability ofthe terminal device does not exist in the second terminal device accesscapability set.

S407: The core network device obtains, in the second terminal deviceaccess capability set, the first access capability indicationinformation corresponding to the radio access capability of the terminaldevice.

The core network device determines the target radio access capabilityconsistent with the radio access capability of the terminal device, thatis, the target radio access capability is the radio access capability ofthe terminal device. Therefore, that the core network device obtains, inthe second terminal device access capability set, the first accesscapability indication information corresponding to the target radioaccess capability is that the core network device obtains the firstaccess capability indication information corresponding to the radioaccess capability of the terminal device.

After S407, S409 may be further performed.

S408: The core network device sets the first access capabilityindication information consistent with the radio access capability ofthe terminal device, and correspondingly adds the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the second terminal deviceaccess capability set.

When the target radio access capability consistent with the radio accesscapability of the terminal device does not exist in the second terminaldevice access capability set, the core network device may set the firstaccess capability indication information consistent with the radioaccess capability of the terminal device, and correspondingly adds thefirst access capability indication information of the terminal deviceand the radio access capability of the terminal device to the secondterminal device access capability set, that is, completes setting of thefirst access capability indication information corresponding to theradio access capability of the terminal device and an update of thesecond terminal device access capability set, so that when the terminaldevice reenters a connected mode, the core network device can directlyfind, in the second terminal device access capability set, the radioaccess capability that is of the terminal device and that corresponds tothe first access capability indication information.

After S408, S409 may alternatively be further performed.

S409: The core network device sends the first access capabilityindication information to the access network device.

After S409, S410 may be further performed, and S411 may also be furtherperformed.

A sequence in which S410 and S411 are performed is not limited. Thesequence in which S410 and S411 are performed may be adjusted based onrequirements, or S410 and S411 may be performed simultaneously.

S410: The access network device correspondingly adds the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the first terminal deviceaccess capability set.

The access network device correspondingly adds the radio accesscapability of the terminal device that is obtained from the terminaldevice and the first access capability indication information of theterminal device that is obtained from the core network device to thefirst terminal device access capability set, that is, completes anupdate of the first terminal device access capability set. In this way,when the terminal device reenters a connected mode, the access networkdevice may directly find, in the first terminal device access capabilityset, the radio access capability that is of the terminal device and thatcorresponds to the first access capability indication informationwithout requesting the terminal device for the radio access capability,so that air interface configuration can be delivered more quickly,communication performance is improved, and an access delay is reduced.

S411: The access network device sends the first access capabilityindication information to the terminal device.

The terminal device may obtain the first access capability indicationinformation of the terminal device, so that when subsequently entering aconnected mode, the terminal device can send the first access capabilityindication information in the RRC connection setup procedure, to performprocesses of the embodiments shown in FIG. 2a to FIG. 4c -2. Further, ifthe second terminal device access capability set in the core networkdevice is not deleted or changed, when receiving the first accesscapability indication information, the access network device maydetermine that the radio access capability that is of the terminal andthat corresponds to the first access capability indication informationexists in the core network device, and then can directly request thecore network device for the radio access capability that is of theterminal and that corresponds to the first access capability indicationinformation. Certainly, if the radio access capability that is of theterminal and that corresponds to the first access capability indicationinformation has existed in the first terminal device access capabilityset in the access network device, the radio access capability of theterminal can be directly obtained locally.

It should be noted that in this embodiment, the first access capabilityindication information, that is, the radio access capability identifier,may be of a PLMN (Public Land Mobile Network, public land mobilenetwork) level. To be specific, the radio access capability identifieris valid in a current PLMN. If the terminal device obtains the radioaccess capability identifier and does not change a PLMN, the terminaldevice carries the radio access capability identifier when subsequentlyentering a connected mode. Alternatively, the radio access capabilityidentifier may be of a core network level. To be specific, the radioaccess capability identifier is valid in a current core network. If theterminal device obtains the radio access capability identifier and doesnot change a core network, the terminal device carries the radio accesscapability identifier when subsequently entering a connected mode.

Optionally, when the access network device needs to hand over theterminal device to a target access network device, this embodiment mayfurther include the following.

S412: When it is determined to perform access network device handover onthe terminal device, the access network device sends a fourth messagecarrying the first access capability indication information to thetarget access network device.

Refer to S109 for a specific implementation of S412, and details are notdescribed herein again.

Optionally, before S402, S401 may be further performed.

S401: Obtain the first terminal device access capability set.

Refer to S301 for a specific implementation of S401, and details are notdescribed herein again.

In the embodiment shown in FIG. 5a -1 to FIG. 5b -2, the access networkdevice does not receive the first access capability indicationinformation of the terminal device in the RRC connection setupprocedure, and it may indicate that the core network device does notknow the first access capability indication information corresponding tothe radio access capability of the terminal device, so that the corenetwork device directly requests the terminal device for the radioaccess capability of the terminal device, to obtain the radio accesscapability of the terminal device more quickly, thereby delivering airinterface configuration, improving communication performance, andreducing an access delay.

The embodiment shown in FIG. 5a -1 to FIG. 5b -2 is applicable to animplementation scenario in which the core network device and the accessnetwork device separately maintain and store the radio access capabilityof the terminal device, and is also applicable to another scenario inwhich the steps of this solution can be performed. This is notspecifically limited herein.

It may be understood that the communication method for handing over theterminal device to the target access network device by the accessnetwork device in the embodiments shown in FIG. 2a to FIG. 5b -2 isapplicable to any scenario in which access network device handover needsto be performed. Therefore, the communication method during the accessnetwork device handover may also be separately implemented independentlyof other embodiments.

FIG. 6 is a schematic flowchart of another communication methodaccording to an embodiment of this application. In this embodiment, anexecution body may be a network device applicable to this implementationscenario, for example, a core network device or an access networkdevice. The method includes but is not limited to the following steps.

S501: Receive a radio access capability of a terminal device.

In an implementation scenario in which the execution body is the corenetwork device, the core network device may directly receive the radioaccess capability sent by the terminal device, or receive the radioaccess capability of the terminal device that is sent by the accessnetwork device. The radio access capability of the terminal device isusually sent to the core network device by the access network deviceafter the access network device requests the terminal device for theradio access capability. In this implementation scenario, the radioaccess capability of the terminal device may be carried by a terminaldevice access capability information indication (UE CAPABILITY INFOINDICATION). This is not specifically limited herein.

In an implementation scenario in which the execution body is the accessnetwork device, the access network device may receive the radio accesscapability of the terminal device that is sent by the core networkdevice, or receive the radio access capability of the terminal devicethat is sent by the terminal device. In this implementation scenario,the radio access capability of the terminal device that is sent by theaccess network device may be carried by a terminal device context setuprequest (UE CONTEXT SETUP REQUEST). The radio access capability of theterminal device that is sent by the terminal device may be carried by aterminal device access capability information indication (UE CAPABILITYINFO INDICATION).

Further, the radio access capability of the terminal device may also beobtained by other means. This is not specifically limited herein.

S502: Detect whether a target radio access capability the same as thereceived radio access capability of the terminal device exists in athird terminal device access capability set. If the target radio accesscapability exists, S503 is performed, and if the target radio accesscapability does not exist, S504 is performed.

The third terminal device access capability set is a set of radio accesscapability information. The radio access capability information may be aradio access capability. The radio access capability information mayfurther include one or more eigenvalues corresponding to the radioaccess capability. Further, the radio access capability information mayfurther include indication information corresponding to the radio accesscapability. Certainly, the third terminal device access capability setmay also include other information. An eigenvalue may be acharacteristic parameter that reflects a radio access capability, forexample, a cyclic redundancy check. The indication information may beterminal device model information or a radio access capabilityidentifier, or may be an identifier formed by combining numerals,symbols, text, or the like.

In an implementation scenario in which the execution body is the accessnetwork device, in consideration of that the access network device mayobtain an ASN.1 encoded byte stream in S501, the access network deviceneeds to perform decoding to use the radio access capability of theterminal device. Therefore, a radio access capability in each piece ofradio access capability information in the third terminal device accesscapability set may be specifically an ASN.1 encoded byte stream.Alternatively, both the ASN.1 encoded byte stream and the ASN.1 decodedradio access capability may be included, so that a base station candirectly use the ASN.1 decoded radio access capability, and does notneed to perform decoding and store the decoded radio access capabilityfor a plurality of times, to reduce processing overheads and storageoverheads.

For example, Table 3 and Table 4 may indicate a plurality of pieces ofradio access capability information in the third terminal device accesscapability set. Table 3 is a case in which the third terminal deviceaccess capability set includes only radio access capabilities. Table 4is a case in which the third terminal device access capability setincludes radio access capabilities and one or more eigenvaluescorresponding thereto. Table 5 is a case in which the third terminaldevice access capability set includes radio access capabilities, andalso includes one or more eigenvalues corresponding to the radio accesscapabilities and access capability indication information correspondingto the radio access capabilities.

TABLE 3 Third terminal device access capability set Radio accesscapability (ASN.1 encoded byte stream or/and ASN.1 decoded radio accesscapability) Radio access capability A Radio access capability B Radioaccess capability C . . .

TABLE 4 Third terminal device access capability set Eigenvalue (Cyclicredundancy check) Radio access capability 1001 Radio access capability A0100 Radio access capability B 1110 Radio access capability C . . . . ..

TABLE 5 Third terminal device access capability set Access capabilityEigenvalue indication information (Cyclic (Radio access capabilityredundancy identifier) check) Radio access capability C1 1001 Radioaccess capability A C2 0100 Radio access capability B C3 1110 Radioaccess capability C . . . . . . . . .

After obtaining the radio access capability of the terminal device, thecore network device or the access network device may detect whether thetarget radio access capability the same as the received radio accesscapability of the terminal device exists in the third terminal deviceaccess capability set.

In a possible implementation scenario, the core network device or theaccess network device may sequentially compare byte streams of radioaccess capabilities in the third terminal device access capability setwith a byte stream of the radio access capability of the terminaldevice. If a first access capability having a byte stream consistentwith the byte stream of the radio access capability of the terminaldevice exists, the first access capability is determined as a targetradio access capability. In other words, the target radio accesscapability exists in the third terminal device access capability set.

In another possible implementation scenario, the core network device orthe access network device may first compare byte stream lengths of radioaccess capabilities in the third terminal device access capability setwith a byte stream length of the radio access capability of the terminaldevice. If a radio access capability having a byte stream lengthconsistent with the byte stream length of the radio access capability ofthe terminal device exists, a byte stream of the radio access capabilityhaving the consistent byte stream length is further compared with thebyte stream of the radio access capability of the terminal device, todetermine whether a target radio access capability exists. If a radioaccess capability having a byte stream length consistent with the bytestream length of the radio access capability of the terminal device doesnot exist, it may be directly determined that the target radio accesscapability does not exist.

In still another possible implementation scenario, when receiving theradio access capability of the terminal device, the core network deviceor the access network device also receives an eigenvalue (for example, acyclic redundancy check (CRC)) for the radio access capability of theterminal device. The eigenvalue may be obtained by calculating the radioaccess capability of the terminal device based on a preset algorithm. Aneigenvalue corresponding to each radio access capability is also storedin the third terminal device access capability set. Therefore, whenreceiving the radio access capability of the terminal device, the corenetwork device or the access network device may first compareeigenvalues of radio access capabilities in the third terminal deviceaccess capability set with an eigenvalue of the radio access capabilityof the terminal device. If a radio access capability having aneigenvalue consistent with the eigenvalue of the radio access capabilityof the terminal device exists, a byte stream of the radio accesscapability having the consistent eigenvalue is further compared with thebyte stream of the radio access capability of the terminal device, todetermine whether a target radio access capability exists. If a radioaccess capability having an eigenvalue consistent with the eigenvalue ofthe radio access capability of the terminal device does not exist, itmay be directly determined that the target radio access capability doesnot exist. It is worth mentioning that there may be a plurality ofeigenvalues herein, and byte streams need to be compared only when theplurality of eigenvalues are all consistent.

Further, the two manners, that is, byte stream length comparison andeigenvalue comparison may alternatively be combined. For example, thebyte stream lengths of the radio capabilities in the third terminaldevice access capability set may be first compared with the byte streamlength of the radio access capability of the terminal device, and thenan eigenvalue of the radio access capability having the consistent bytestream length is compared with the eigenvalue of the radio accesscapability of the terminal device, and finally the byte stream of theradio access capability having the consistent eigenvalue is comparedwith the byte stream of the radio access capability of the terminaldevice, to determine whether the target radio access capability exists.Similarly, alternatively, the eigenvalues may be first compared, thenthe byte stream lengths are compared, and finally the byte streams arecompared. This is not specifically limited in this embodiment.

In the foregoing several possible implementation scenarios, a quantityof times of radio access capability comparison can be reduced, so thatprocessing load of a system is reduced.

S503: Index second access capability indication information in a contextof the terminal device to radio access capability informationcorresponding to the target radio access capability.

The context of the terminal device may include some parameters orinformation, such as features, algorithms, bearers, and keys, requiredfor the terminal device to perform communication, and includes the radioaccess capability of the terminal device. Generally, the core networkdevice or the access network device may store the context of theterminal device. In this embodiment, the core network device or theaccess network device does not directly store the radio accesscapability of the terminal device in the context, and instead, the corenetwork device or the access network device introduces the second accesscapability indication information into the context of the terminaldevice. The second access capability indication information may be usedand be indexed to the radio access capability of the terminal device.

Optionally, when determining that the radio access capability of theterminal device is the target radio access capability, the core networkdevice or the access network device may index the second accesscapability indication information in the context of the terminal deviceto the radio access capability information corresponding to the targetradio access capability. In other words, an index is set up for thesecond access capability indication information in the context of theterminal device, and the index is directed to the radio accesscapability information corresponding to the target radio accesscapability.

In a possible implementation scenario, the second access capabilityindication information may be address information, for being directed toa radio access capability stored in a storage space corresponding to theaddress information by the third terminal device access capability set.For example, when the third terminal device access capability set is anarray, the second access capability indication information is an arraysubscript in the array. For example, as shown in FIG. 8 a, the contextof the terminal device that is stored by the core network device or theaccess network device does not directly store the radio accesscapability of the terminal device, and instead, stores the second accesscapability indication information, that is, the array subscript. It isassumed that an array name of the third terminal device radio accesscapability set is a, and an array subscript (for example, 0) maycorrespond to a radio access capability (a[0]) in the third terminaldevice access capability set. Therefore, assuming that the target radioaccess capability is determined as the radio access capability indicatedby a[1], the second access capability indication information in thecontext of the terminal device may be set to a[1], so that the secondaccess capability indication information in the context of the terminaldevice can be indexed to the radio access capability informationcorresponding to the target radio access capability.

In another possible implementation scenario, the second accesscapability indication information may be terminal device modelinformation or a radio access capability identifier, or an identifierformed by combining numerals, symbols, text, or the like. For example,as shown in FIG. 8 b, the context of the terminal device that is storedby the core network device or the access network device does notdirectly store the radio access capability of the terminal device, andinstead, stores the second access capability indication information, forexample, a radio access capability identifier. Assuming that the targetradio access capability is determined as the radio access capabilityindicated by a radio access capability identifier C1, the second accesscapability indication information in the context of the terminal devicemay be set to C1, so that the second access capability indicationinformation in the context of the terminal device can be indexed to theradio access capability information corresponding to the target radioaccess capability.

S504: Add the radio access capability information corresponding to theradio access capability of the terminal device to the third terminaldevice access capability set, and index the second access capabilityindication information in the context of the terminal device to theadded radio access capability information.

When the target radio access capability does not exist in the thirdterminal device access capability set, the core network device or theaccess network device may add the radio access capability informationcorresponding to the radio access capability of the terminal device tothe third terminal device access capability set. The radio accesscapability information may be the radio access capability of theterminal device, or the radio access capability of the terminal deviceand one or more eigenvalues corresponding to the radio access capabilityof the terminal device. Then, the second access capability indicationinformation in the context of the terminal device is indexed to theadded radio access capability information.

In the embodiment shown in FIG. 6, by comparing the byte streams, it canbe ensured that for same radio access capabilities, only one radioaccess capability is stored. In other words, even if terminal devicesare of different types, provided that the terminal devices have sameradio access capabilities, only one radio access capability needs to bestored. The context does not store the radio access capability of theterminal device, and instead, stores the second access capabilityindication information for being indexed to the radio access capabilityof the terminal device, so that memory occupation of the access networkdevice and the core network device by storage of the radio accesscapability of the terminal device can be reduced.

It may be understood that the communication method described in theembodiment shown in FIG. 6 is applicable to any scenario in which theradio access capability of the terminal device is stored. Optionally,the method in the embodiment shown in FIG. 6 may be independent of otherembodiments, or may be combined with the other embodiments. For example,in the embodiment shown in FIG. 2 b, after the access network devicecorrespondingly adds the first access capability indication informationof the terminal device and the radio access capability of the terminaldevice to the first terminal device access capability set, the contextof the terminal device may not store the radio access capability of theterminal device, and instead, the first access capability indicationinformation is used as the second access capability indicationinformation, and the second access capability indication information inthe context is indexed to the radio access capability of the terminaldevice that is stored in the first terminal device access capabilityset.

It should be noted that each time the first terminal device accesscapability set, the second terminal device access capability set, andthe third terminal device access capability set in the embodiments shownin FIG. 2a to FIG. 6 store a radio access capability, timing on astorage time of the radio access capability may start. When it isdetected that the storage time of the radio access capability exceeds apreset valid time interval, it is considered that the radio accesscapability fails, and the radio access capability may be further deletedfrom the foregoing sets.

FIG. 7 is a schematic flowchart of another communication methodaccording to an embodiment of this application. The method includes butis not limited to the following steps.

S601: A terminal device sends access capability temporary limitinformation to an access network device.

In this embodiment, a current radio access capability of the terminaldevice that is determined by the access network device may depend on astatic radio access capability and the access capability temporary limitinformation of the terminal device. The static radio access capabilityof the terminal device includes all implementable radio accesscapabilities owned by the terminal device, or may be considered as amost complete set of radio access capabilities of the terminal device.The access capability temporary limit information of the terminal deviceis used to indicate a limited capability in the static radio accesscapability of the terminal device, that is, a radio access capabilitythat cannot be currently used or that has a limited use degree of theterminal device.

Further, in a possible implementation scenario, the access capabilitytemporary limit information may be carried by an RRC connection requestmessage or an RRC connection setup complete message. In another possibleimplementation scenario, if the access capability temporary limitinformation changes when the terminal device is inactive (inactive),when UE recovers to a connected mode, the terminal device may add theaccess capability temporary limit information to an RRC connectionrecovery request or an RRC connection recovery complete message, andsends the RRC connection recovery request or RRC connection recoverycomplete message that carries the access capability temporary limitinformation to the access network device. In other words, the accesscapability temporary limit information may be carried by the RRCconnection recovery request or the RRC connection recovery completemessage.

Optionally, when the terminal device is in a connected mode, the accesscapability temporary limit information of the terminal device may changefor a plurality of times. Therefore, in a possible implementationscenario, when sending the access capability temporary limit informationto the access network device, the terminal device can always reportcurrently complete access capability temporary limit information. Theaccess network device replaces existing access capability temporarylimit information with the received temporary limit information ascurrently used access capability temporary limit information. In anotherpossible implementation scenario, when sending the access capabilitytemporary limit information to the access network device, the terminaldevice reports only limit information that changes relative to currentlyused access capability temporary limit information of the access networkdevice, and the access network device generates new access capabilitytemporary limit information based on the currently used accesscapability temporary limit information and the limit information thatchanges.

Further optionally, the terminal device may support a plurality ofmobile communications standards. When reporting the access capabilitytemporary limit information, the terminal device may report onlyrelevant access capability temporary limit information of a mobilecommunications standard related to current terminal device access, toreduce signaling overheads.

S602: The access network device determines a current radio accesscapability of the terminal device based on the access capabilitytemporary limit information of the terminal device and the static radioaccess capability of the terminal device.

In a possible implementation scenario, the access network device hasobtained the static radio access capability of the terminal device, andthen can directly determine the current radio access capability of theterminal device, that is, a current actually available radio accesscapability of the terminal device, based on the access capabilitytemporary limit information of the terminal device and the static radioaccess capability of the terminal device.

In another possible implementation scenario, the access network devicehas not obtained the static radio access capability of the terminaldevice, and then the access network device may first obtain the staticradio access capability of the terminal device, or obtain the staticradio access capability and the access capability temporary limitinformation of the terminal device simultaneously, and then determinethe current radio access capability of the terminal device based on theaccess capability temporary limit information of the terminal device andthe static radio access capability of the terminal device.

A specific method for obtaining the static radio access capability ofthe terminal device may be an obtaining method in the prior art, or anobtaining method in the embodiments shown in FIG. 2a to FIG. 5b -2. Thisis not specifically limited herein.

Further, after S602, S603 may be further performed.

S603: The access network device performs air interface configuration onthe terminal device based on the current radio access capability of theterminal device.

Refer to S108 for a specific implementation of S603, and details are notdescribed herein again.

Optionally, when the access network device needs to hand over theterminal device to a target access network device, this embodiment mayfurther include the following.

S604. When it is determined to perform access network device handover onthe terminal device, the access network device sends a fourth messagecarrying the access capability temporary limit information to the targetaccess network device.

The access network device determines the target access network device towhich the terminal device needs to be handed over, and sends the fourthmessage to the target access network device. The fourth message carriesthe access capability temporary limit information of the terminaldevice. The fourth message is used to instruct the target access networkdevice to determine the current radio access capability of the terminaldevice based on the access capability temporary limit information.Further, the fourth message may be a handover request message, that is,Handover Request.

In the embodiment shown in FIG. 7, the radio access capability of theterminal device may depend on the static radio access capability and theaccess capability temporary limit information of the terminal device.When the radio access capability of the terminal device changes as ascenario changes, the terminal device only needs to send the accesscapability temporary limit information to the access network device, sothat signaling overheads between the terminal device and the accessnetwork device can be reduced.

It may be understood that the communication method described in theembodiment shown in FIG. 7 is applicable to any scenario in which theradio access capability of the terminal device is determined based onthe static radio access capability and the access capability temporarylimit information. Optionally, the method in the embodiment shown inFIG. 7 may be independent of other embodiments, or may be combined withthe other embodiments.

An embodiment of this application provides an access network device. Theaccess network device may implement functions of the access networkdevice in the method described in the foregoing embodiment of thisapplication.

Optionally, FIG. 9 is a schematic structural diagram of an accessnetwork device according to an embodiment of the present invention. Asshown in FIG. 9, the access network device 900 includes a receivingmodule 901, configured to in a radio resource control RRC connectionsetup procedure, receive first access capability indication informationof a terminal device, where the first access capability indicationinformation is used to represent a radio access capability of theterminal device, and a processing module 902, configured to obtain theradio access capability of the terminal device according to the firstaccess capability indication information.

Optionally, the processing module 902 is configured to use a radioaccess capability that corresponds to the first access capabilityindication information and that is in a first terminal device accesscapability set as the radio access capability of the terminal deviceaccording to the first access capability indication information.

Optionally, the access network device 900 further includes a sendingmodule 903, configured to when the access network device does not storethe radio access capability that corresponds to the first accesscapability indication information, request the terminal device or a corenetwork device for the radio access capability of the terminal device.

Optionally, the receiving module 901 is further configured to receiveterminal device access capability information sent by the terminaldevice, where the terminal device access capability information includesthe radio access capability of the terminal device, and the processingmodule 902 is further configured to correspondingly add the first accesscapability indication information of the terminal device and the radioaccess capability of the terminal device to the first terminal deviceaccess capability set.

Optionally, the sending module 903 is configured to send a first messageto the core network device, where the first message is used to indicatethat the access network device has obtained the radio access capabilityof the terminal device.

Optionally, the receiving module 901 is further configured to receive athird message from the core network device, and the processing module902 is further configured to when the third message carries the radioaccess capability of the terminal device, correspondingly add the firstaccess capability indication information of the terminal device and theradio access capability of the terminal device to the first terminaldevice access capability set.

Optionally, the sending module 903 is configured to when it isdetermined to perform access network device handover on the terminaldevice, send a fourth message carrying the first access capabilityindication information to a target access network device.

It should be referred to related descriptions of the correspondingaccess network device in the embodiments shown in FIG. 2a to FIG. 7 forfunctions and implementations of the functional modules in the accessnetwork device 900 described in this embodiment of this application andmeanings and obtaining manners of related parameters. Details are notdescribed herein again.

An embodiment of this application provides a terminal device. Theterminal device may implement functions of the terminal device in themethod described in the foregoing embodiment of this application.

Optionally, FIG. 10 is a schematic structural diagram of a terminaldevice according to an embodiment of the present invention. As shown inFIG. 10, the terminal device woo includes a processing module 1001,configured to obtain first access capability indication information ofthe terminal device, and a sending module 1002, configured to in a radioresource control RRC connection setup procedure, send the first accesscapability indication information of the terminal device to an accessnetwork device, where the first access capability indication informationis used to represent a radio access capability of the terminal device.

Optionally, the terminal device moo further includes a receiving module1003, configured to when a radio access capability corresponding to thefirst access capability indication information does not exist in a firstterminal device access capability set, receive a terminal device accesscapability request from the access network device.

It should be referred to related descriptions of the correspondingterminal device in the embodiments shown in FIG. 2a to FIG. 7 forfunctions and implementations of the functional modules in the terminaldevice woo described in this embodiment of this application and meaningsand obtaining manners of related parameters. Details are not describedherein again.

An embodiment of this application provides a core network device. Thecore network device may implement functions of the core network devicein the method described in the foregoing embodiment of this application.

Optionally, FIG. 11 is a schematic structural diagram of a core networkdevice according to an embodiment of the present invention. As shown inFIG. 11, the core network device 1100 includes a receiving module 1101,configured to receive a second message from an access network device,where the second message carries first access capability indicationinformation of a terminal, and the first access capability indicationinformation is used to represent a radio access capability of theterminal, and a processing module 1102, configured to obtain the radioaccess capability of the terminal according to the first accesscapability indication information of the terminal.

Optionally, the processing module 1102 is specifically configured to usea radio access capability that corresponds to the first accesscapability indication information and that is in a second terminalaccess capability set as the radio access capability of the terminalaccording to the first access capability indication information.

The core network device 1100 further includes a sending module 1103,configured to send the obtained radio access capability of the terminalto the access network device.

Optionally, the sending module 1103 is further configured to when theradio access capability corresponding to the first access capabilityindication information does not exist in the second terminal accesscapability set, instruct the access network device to request theterminal for the radio access capability of the terminal.

Optionally, the receiving module 1101 is further configured to receivethe radio access capability of the terminal from the access networkdevice.

The processing module 1102 is further configured to correspondingly addthe first access capability indication information of the terminal andthe radio access capability of the terminal to the second terminalaccess capability set.

It should be referred to related descriptions of the corresponding corenetwork device in the embodiments shown in FIG. 2a to FIG. 7 forfunctions and implementations of the functional modules in the corenetwork device 1100 described in this embodiment of this application andmeanings and obtaining manners of related parameters. Details are notdescribed herein again.

An embodiment of this application provides a network device. The networkdevice may implement functions of the network device in the methoddescribed in the foregoing embodiment of this application.

Optionally, FIG. 12 is a schematic structural diagram of a networkdevice according to an embodiment of the present invention. As shown inFIG. 12, the network device 1200 includes a receiving module 1201,configured to receive a radio access capability of a terminal device,and a processing module 1202, configured to detect whether a targetradio access capability the same as the received radio access capabilityof the terminal device exists in a third terminal device accesscapability set, where the third terminal device access capability set isa set of radio access capability information.

The processing module 1202 is further configured to when the targetradio access capability exists in the third terminal device accesscapability set, index second access capability indication information ina context of the terminal device to the target radio access capability.

Optionally, the processing module 1202 is further configured to when thetarget radio access capability does not exist in the third terminaldevice access capability set, add radio access capability informationcorresponding to the radio access capability of the terminal device tothe third terminal device access capability set, and index the secondaccess capability indication information in the context of the terminaldevice to the added radio access capability information.

Optionally, the processing module 1202 is specifically configured todetermine a first access capability that has a byte stream the same asthat of the radio access capability of the terminal device and that isin the third terminal device access capability set as the target radioaccess capability.

It should be referred to related descriptions of the corresponding corenetwork device or access network device in the embodiment shown in FIG.6 for functions and implementations of the functional modules in thenetwork device 1200 described in this embodiment of this application andmeanings and obtaining manners of related parameters. Details are notdescribed herein again.

FIG. 13 is a schematic structural diagram of another access networkdevice according to an embodiment of this application. As shown in FIG.13, the access network device 1300 includes a processor 131, a memory132, and a communications interface 133. The processor 131 is connectedto the memory 132 and the communications interface 133. For example, theprocessor 131 may be connected to the memory 132 and the communicationsinterface 133 by using a bus.

The processor 131 is configured to support the access network device inperforming corresponding functions in the methods in FIG. 2a to FIG. 7.The processor 131 may be a central processing unit (CPU), a networkprocessor (NP), a hardware chip, or any combination thereof. Thehardware chip may be an application-specific integrated circuit (ASIC),a programmable logic device (PLD), or a combination thereof. The PLD maybe a complex programmable logic device (CPLD), a field-programmable gatearray (FPGA), a generic array logic (GAL), or any combination thereof.

The memory 132 is configured to store program code, a radio accesscapability, and the like. The memory 132 may include a volatile memory,for example, a random access memory (RAM). The memory 132 may alsoinclude a non-volatile memory, for example, a read-only memory (ROM), aflash memory), a hard disk drive (HDD), or a solid-state drive (SSD).The memory 132 may also include a combination of memories of theforegoing types.

The communications interface 133 is configured to communicate withanother network device in this embodiment of this application.

The processor 131 in the access network device 1300 reads the programcode stored in the memory 132, so that the following operations areperformed.

The communications interface 133 is configured to in a radio resourcecontrol RRC connection setup procedure, receive first access capabilityindication information of a terminal device, where the first accesscapability indication information is used to represent a radio accesscapability of the terminal device.

The processor 131 is configured to obtain the radio access capability ofthe terminal device according to the first access capability indicationinformation.

Optionally, the processor 131 is specifically configured to use a radioaccess capability that corresponds to the first access capabilityindication information and that is in a first terminal device accesscapability set as the radio access capability of the terminal deviceaccording to the first access capability indication information.

Optionally, the communications interface 133 is further configured towhen the access network device does not store the radio accesscapability that corresponds to the first access capability indicationinformation, request the terminal device or a core network device forthe radio access capability of the terminal device.

Optionally, the communications interface 133 is further configured toreceive terminal device access capability information sent by theterminal device, where the terminal device access capability informationincludes the radio access capability of the terminal device.

The processor 131 is further configured to correspondingly add the firstaccess capability indication information of the terminal device and theradio access capability of the terminal device to the first terminaldevice access capability set.

Optionally, the communications interface 133 is further configured tosend a first message to the core network device, where the first messageis used to indicate that the access network device has obtained theradio access capability of the terminal device.

Optionally, the communications interface 133 is further configured toreceive a third message from the core network device.

The processor 131 is further configured to when the third messagecarries the radio access capability of the terminal device,correspondingly add the first access capability indication informationof the terminal device and the radio access capability of the terminaldevice to the first terminal device access capability set.

Optionally, the communications interface 133 is further configured towhen it is determined to perform access network device handover on theterminal device, send a fourth message carrying the first accesscapability indication information to a target access network device.

It should be referred to related descriptions of the correspondingaccess network device in the embodiments shown in FIG. 2a to FIG. 7 forfunctions of the functional modules in the access network device 1300.Details are not described herein again. Optionally, the processor 131may be configured to implement the function of the processing module902, and the communications interface 133 may be configured to implementthe functions of one or more modules in the receiving module 901 or thesending module 903. In the several embodiments provided in thisapplication, it should be understood that the disclosed apparatus andmethod may be implemented in other manners. For example, the describedapparatus embodiment is merely exemplary. For example, the moduledivision is merely logical function division and may be other divisionin actual implementation. For example, a plurality of modules orcomponents may be combined or integrated into another system, or somefeatures may be ignored or not performed. In addition, the displayed ordiscussed mutual couplings or direct couplings or communicationconnections may be implemented through some interfaces. The indirectcouplings or communication connections between the apparatuses ormodules may be implemented in electronic, mechanical, or other forms.

FIG. 14 is a schematic structural diagram of another terminal deviceaccording to an embodiment of this application. As shown in FIG. 14, theterminal device 1400 includes a processor 141, a memory 142, and acommunications interface 143. The processor 141 is connected to thememory 142 and the communications interface 143. For example, theprocessor 141 may be connected to the memory 142 and the communicationsinterface 143 by using a bus.

The processor 141 is configured to support the terminal device inperforming corresponding functions in the methods in FIG. 2a to FIG. 7.The processor 141 may be a central processing unit (CPU), a networkprocessor (NP), a hardware chip, or any combination thereof. Thehardware chip may be an application-specific integrated circuit (ASIC),a programmable logic device (PLD), or a combination thereof. The PLD maybe a complex programmable logic device (CPLD), a field-programmable gatearray (FPGA), a generic array logic (GAL), or any combination thereof.

The memory 142 is configured to store program code, a radio accesscapability, and the like. The memory 142 may include a volatile memory,for example, a random access memory (RAM). The memory 142 may alsoinclude a non-volatile memory, for example, a read-only memory (ROM), aflash memory, a hard disk drive (HDD), or a solid-state drive (SSD). Thememory 142 may also include a combination of memories of the foregoingtypes.

The communications interface 143 is configured to communicate withanother network device in this embodiment of this application.

The processor 141 in the terminal device 1400 reads the program codestored in the memory 142, so that the following operations areperformed.

The processor 141 is configured to obtain first access capabilityindication information of the terminal device.

The communications interface 143 is configured to in a radio resourcecontrol RRC connection setup procedure, send the first access capabilityindication information of the terminal device to an access networkdevice, where the first access capability indication information is usedto represent a radio access capability of the terminal device.

Optionally, the communications interface 143 is further configured towhen a radio access capability corresponding to the first accesscapability indication information does not exist in a first terminaldevice access capability set, receive a terminal device accesscapability request from the access network device.

It should be referred to related descriptions of the correspondingterminal device in the embodiments shown in FIG. 2a to FIG. 7 forfunctions of the functional modules in the terminal device 1400. Detailsare not described herein again. Optionally, the processor 141 may beconfigured to implement the function of the processing module 1001, andthe communications interface 143 may be configured to implement thefunctions of one or more modules in the receiving module 1003 or thesending module 1002. In the several embodiments provided in thisapplication, it should be understood that the disclosed apparatus andmethod may be implemented in other manners. For example, the describedapparatus embodiment is merely exemplary. For example, the moduledivision is merely logical function division and may be other divisionin actual implementation. For example, a plurality of modules orcomponents may be combined or integrated into another system, or somefeatures may be ignored or not performed. In addition, the displayed ordiscussed mutual couplings or direct couplings or communicationconnections may be implemented through some interfaces. The indirectcouplings or communication connections between the apparatuses ormodules may be implemented in electronic, mechanical, or other forms.

FIG. 15 is a schematic structural diagram of another core network deviceaccording to an embodiment of this application. As shown in FIG. 15, thecore network device 1500 includes a processor 151, a memory 152, and acommunications interface 153. The processor 151 is connected to thememory 152 and the communications interface 153. For example, theprocessor 151 may be connected to the memory 152 and the communicationsinterface 153 by using a bus.

The processor 151 is configured to support the core network device inperforming corresponding functions in the methods in FIG. 2a to FIG. 7.The processor 151 may be a central processing unit (CPU), a networkprocessor (NP), a hardware chip, or any combination thereof. Thehardware chip may be an application-specific integrated circuit (ASIC),a programmable logic device (PLD), or a combination thereof. The PLD maybe a complex programmable logic device (CPLD), a field-programmable gatearray (FPGA), a generic array logic (GAL), or any combination thereof.

The memory 152 is configured to store program code, a radio accesscapability, and the like. The memory 152 may include a volatile memory,for example, a random access memory (RAM). The memory 152 may alsoinclude a non-volatile memory, for example, a read-only memory (ROM), aflash memory, a hard disk drive (HDD), or a solid-state drive (SSD). Thememory 152 may also include a combination of memories of the foregoingtypes.

The communications interface 153 is configured to communicate withanother network device in this embodiment of this application.

The processor 151 in the core network device 1500 reads the program codestored in the memory 152, so that the following operations areperformed.

The communications interface 153 is configured to receive a secondmessage from an access network device, where the second message carriesfirst access capability indication information of a terminal, and thefirst access capability indication information is used to represent aradio access capability of the terminal.

The processor 151 is configured to obtain the radio access capability ofthe terminal according to the first access capability indicationinformation of the terminal.

Optionally, the communications interface 153 is specifically configuredto use a radio access capability that corresponds to the first accesscapability indication information and that is in a second terminalaccess capability set as the radio access capability of the terminalaccording to the first access capability indication information.

The communications interface 153 is further configured to send theobtained radio access capability of the terminal to the access networkdevice.

Optionally, the communications interface 153 is further configured to

when the radio access capability corresponding to the first accesscapability indication information does not exist in the second terminalaccess capability set, instruct the access network device to request theterminal for the radio access capability of the terminal.

Optionally, the communications interface 153 is further configured toreceive the radio access capability of the terminal from the accessnetwork device.

The processor 151 is further configured to correspondingly add the firstaccess capability indication information of the terminal and the radioaccess capability of the terminal to the second terminal accesscapability set.

It should be referred to related descriptions of the corresponding corenetwork device in the embodiments shown in FIG. 2a to FIG. 7 forfunctions of the functional modules in the core network device 1500.Details are not described herein again. Optionally, the processor 151may be configured to implement the function of the processing module1102, and the communications interface 153 may be configured toimplement the functions of one or more modules in the receiving module1101 or the sending module 1103. In the several embodiments provided inthis application, it should be understood that the disclosed apparatusand method may be implemented in other manners. For example, thedescribed apparatus embodiment is merely exemplary. For example, themodule division is merely logical function division and may be otherdivision in actual implementation. For example, a plurality of modulesor components may be combined or integrated into another system, or somefeatures may be ignored or not performed. In addition, the displayed ordiscussed mutual couplings or direct couplings or communicationconnections may be implemented through some interfaces. The indirectcouplings or communication connections between the apparatuses ormodules may be implemented in electronic, mechanical, or other forms.

FIG. 16 is a schematic structural diagram of another network deviceaccording to an embodiment of this application. As shown in FIG. 16, thenetwork device 1600 includes a processor 161, a memory 162, and acommunications interface 163. The processor 161 is connected to thememory 162 and the communications interface 163. For example, theprocessor 161 may be connected to the memory 162 and the communicationsinterface 163 by using a bus.

The processor 161 is configured to support the network device inperforming corresponding functions in the method in FIG. 6. Theprocessor 161 may be a central processing unit (CPU), a networkprocessor (NP), a hardware chip, or any combination thereof. Thehardware chip may be an application-specific integrated circuit (ASIC),a programmable logic device (PLD), or a combination thereof. The PLD maybe a complex programmable logic device (CPLD), a field-programmable gatearray (FPGA), a generic array logic (GAL), or any combination thereof.

The memory 162 is configured to store program code, a radio accesscapability, and the like. The memory 162 may include a volatile memory(volatile memory), for example, a random access memory (RAM). The memory162 may also include a non-volatile memory, for example, a read-onlymemory (ROM), a flash memory, a hard disk drive (HDD), or a solid-statedrive (SSD). The memory 162 may also include a combination of memoriesof the foregoing types.

The communications interface 163 is configured to communicate withanother network device in this embodiment of this application.

The processor 161 in the network device 1600 reads the program codestored in the memory 162, so that the following operations areperformed.

The communications interface 163 is configured to receive a radio accesscapability of a terminal device.

The processor 161 is configured to detect whether a target radio accesscapability the same as the received radio access capability of theterminal device exists in a third terminal device access capability set,where the third terminal device access capability set is a set of radioaccess capability information.

The processor 161 is further configured to when the target radio accesscapability exists in the third terminal device access capability set,index second access capability indication information in a context ofthe terminal device to the target radio access capability.

Optionally, the processor 161 is further configured to when the targetradio access capability does not exist in the third terminal deviceaccess capability set, add radio access capability informationcorresponding to the radio access capability of the terminal device tothe third terminal device access capability set, and index the secondaccess capability indication information in the context of the terminaldevice to the added radio access capability information.

Optionally, the processor 161 is specifically configured to determine afirst access capability that has a byte stream the same as that of theradio access capability of the terminal device and that is in the thirdterminal device access capability set as the target radio accesscapability.

It should be referred to related descriptions of the corresponding corenetwork device or access network device in the embodiment shown in FIG.6 for functions of the functional modules in the network device 1600.Details are not described herein again. Optionally, the processor 161may be configured to implement the function of the processing module1202, and the communications interface 163 may be configured toimplement the function of the receiving module 1201. In the severalembodiments provided in this application, it should be understood thatthe disclosed apparatus and method may be implemented in other manners.For example, the described apparatus embodiment is merely exemplary. Forexample, the module division is merely logical function division and maybe other division in actual implementation. For example, a plurality ofmodules or components may be combined or integrated into another system,or some features may be ignored or not performed. In addition, thedisplayed or discussed mutual couplings or direct couplings orcommunication connections may be implemented through some interfaces.The indirect couplings or communication connections between theapparatuses or modules may be implemented in electronic, mechanical, orother forms.

Persons of ordinary skill in the art may understand that sequencenumbers of the foregoing processes do not mean execution sequences invarious embodiments of this application. The execution sequences of theprocesses should be determined according to functions and internal logicof the processes, and should not be construed as any limitation on theimplementation processes of the embodiments of this application.

All or some of the foregoing embodiments may be implemented by means ofsoftware, hardware, firmware, or any combination thereof. When softwareis used to implement the embodiments, the embodiments may be implementedcompletely or partially in a form of a computer program product. Thecomputer program product includes one or more computer instructions.When the computer program instructions are loaded and executed on thecomputer, the procedure or functions according to the embodiments of thepresent invention are all or partially generated. The computer may be ageneral-purpose computer, a dedicated computer, a computer network, orother programmable apparatuses. The computer instructions may be storedin a computer-readable storage medium or may be transmitted from acomputer-readable storage medium to another computer-readable storagemedium. For example, the computer instructions may be transmitted from awebsite, computer, server, or data center to another website, computer,server, or data center in a wired (for example, a coaxial cable, anoptical fiber, or a digital subscriber line (DSL)) or wireless (forexample, infrared, radio, and microwave, or the like) manner. Thecomputer-readable storage medium may be any usable medium accessible bya computer, or a data storage device, such as a server or a data center,integrating one or more usable media. The usable medium may be amagnetic medium (for example, a floppy disk, a hard disk, or a magnetictape), an optical medium (for example, a DVD), a semiconductor medium(for example, a solid-state drive (SSD)), or the like.

A person of ordinary skill in the art may understand that all or some ofthe processes of the methods in the embodiments may be implemented by acomputer program instructing relevant hardware. The program may bestored in a computer readable storage medium. When the program runs, theprocesses of the methods in the embodiments are performed. The storagemedium may include a magnetic disk, an optical disc, a read-only memory(Read-Only Memory, ROM), or a random access memory (Random AccessMemory, RAM).

What is disclosed above is merely example embodiments of the presentinvention, and certainly is not intended to limit the protection scopeof the present invention. Therefore, equivalent variations made inaccordance with the claims of the present invention shall fall withinthe scope of the present invention.

What is claimed is:
 1. A communication method, comprising: receiving a radio access capability of a terminal device; detecting whether a target radio access capability the same as the received radio access capability of the terminal device exists in a terminal device access capability set, wherein the terminal device access capability set is a set of radio access capability information corresponding to radio access capabilities; and when the target radio access capability exists in the terminal device access capability set, indexing second access capability indication information in a context of the terminal device to radio access capability information corresponding to the target radio access capability.
 2. The method according to claim 1, further comprising: when the target radio access capability does not exist in the terminal device access capability set, adding radio access capability information corresponding to the radio access capability of the terminal device to the terminal device access capability set, and indexing the second access capability indication information in the context of the terminal device to the added radio access capability information.
 3. The method according to claim 1, wherein the detecting whether the target radio access capability the same as the received radio access capability of the terminal device exists in the terminal device access capability set comprises: determining a first access capability that has a byte stream the same as that of the radio access capability of the terminal device and that is in the terminal device access capability set as the target radio access capability.
 4. A communication method, comprising: receiving, in a radio resource control (RRC) connection setup procedure, by an access network device, first access capability indication information of a terminal device, wherein the first access capability indication information is used to represent a radio access capability of the terminal device, and the first access capability indication information is allocated by a core network device; and obtaining, by the access network device, the radio access capability of the terminal device according to the first access capability indication information.
 5. The method according to claim 4, wherein the obtaining, by the access network device, the radio access capability of the terminal device according to the first access capability indication information comprises: using, by the access network device, a radio access capability that corresponds to the first access capability indication information and that is in a first terminal device access capability set as the radio access capability of the terminal device according to the first access capability indication information.
 6. The method according to claim 5, wherein after the using the radio access capability that corresponds to the first access capability indication information and that is in the first terminal device access capability set as the radio access capability of the terminal device, the method further comprises: sending, by the access network device, a first message to the core network device, wherein the first message is used to indicate that the access network device has obtained the radio access capability of the terminal device.
 7. The method according to claim 5, wherein the obtaining, by the access network device, the radio access capability of the terminal device according to the first access capability indication information comprises: when the access network device does not store the radio access capability that corresponds to the first access capability indication information, requesting, by the access network device, the terminal device or a core network device for the radio access capability of the terminal device.
 8. The method according to claim 7, wherein after the access network device requests the terminal device for the radio access capability of the terminal device, the method further comprises: receiving, by the access network device, terminal device access capability information from the terminal device, wherein the terminal device access capability information comprises the radio access capability of the terminal device; and correspondingly adding, by the access network device, the first access capability indication information of the terminal device and the radio access capability of the terminal device to the first terminal device access capability set.
 9. The method according to claim 7, wherein after the access network device requests the core network device for the radio access capability of the terminal device, the method further comprises: receiving, by the access network device, a third message from the core network device; and when the third message carries the radio access capability of the terminal device, correspondingly adding, by the access network device, the first access capability indication information of the terminal device and the radio access capability of the terminal device to the first terminal device access capability set.
 10. The method according to claim 4, wherein the first access capability indication information of the terminal device comprises terminal device model information or a radio access capability identifier.
 11. The method according to claim 4, further comprising: when it is determined to perform access network device handover on the terminal device, sending, by the access network device, a fourth message carrying the first access capability indication information to a target access network device.
 12. The method according to claim 4, wherein the first access capability indication information is carried by an RRC connection request message or an RRC connection setup complete message.
 13. A communication method, comprising: obtaining, by a terminal device, first access capability indication information of the terminal device, wherein the first access capability indication information is allocated by a core network device; and sending, in a radio resource control (RRC) connection setup procedure, by the terminal device, the first access capability indication information of the terminal device to an access network device, wherein the first access capability indication information is used to represent a radio access capability of the terminal device.
 14. The method according to claim 13, further comprising: when a radio access capability corresponding to the first access capability indication information does not exist in a first terminal device access capability set, receiving, by the terminal device, a terminal device access capability request from the access network device.
 15. The method according to claim 13, wherein the first access capability indication information of the terminal device comprises terminal device model information or a radio access capability identifier. 